Cylinder Head Cover (Valve Cover)
Removing and installing cylinder head cover - engine removed (as of MY 02)
Engine type M 96 / 03
Caution
When working on the engine, absolute cleanliness is essential! An engine cover should be used on the engine assembly support. Lay removed engine parts on a clean base and cover them without fail. Even the smallest particles of dirt can block up oil bores.
Removing cylinder head cover - cylinder banks 1 - 3 and 4 - 6
- Preliminary work: engine oil drained.
Cylinder bank 1 - 3
1. Remove the shield (1). Unscrew 2 hexagon-head bolts M6x16. Pull out the shield to the belt pulley side.
2. Remove holder for main muffler (2). Pull off the electrical plug of ignition coil cyl. 2 and the 2 electrical plugs of the magnetic hydraulic valves. Unscrew 4 hexagon-head bolts: top 2 M8x30, bottom 2 M8x25, then pull out the holder towards the clutch side.
3. Remove 3 ignition coils. Unscrew 6 hexagon socket head bolts M6x25 and pull the ignition coils out from the spark-plug recess.
4. Remove 2 holders and 2 covers for the magnetic hydraulic valves. Unscrew 4 hexagon socket head bolts M6x20, disconnect the connection cable for the hydraulic valves from the sheetmetal bracket and remove the holders. Pull off 2 covers for the hydraulic valves. The valves on side 1-3 can remain connected.
- A: Holder for camshaft adjustment valve (NVS)
- B: Holder for valve lift adjustment valve (VVS)
Cover for magnetic hydraulic valves in installation position with integrated seal
Caution
When levering off the cylinder head cover, the cast lugs may break.
5. Remove cylinder head cover. Unscrew the 20 hexagon-head bolts M6x30 from the cylinder head cover and the 2 hexagon-head bolts M6x20, which are screwed to the cover, from the oil extraction pump. To release the cylinder head cover, raise the cover carefully at the two protruding cast edges with a slotted screwdriver. Remove the cylinder head cover on side 1-3.
Levering off the cylinder head cover, Figure shows side 1-3
Information
- Check the O-ring on the oil extraction pump. If the O-ring needs to be replaced, also unscrew the 2 lower hexagon-head bolts M6x20 and remove the pump.
Cylinder bank 4 - 6
1. Remove the ground cable from the cylinder head. Unscrew 1 hexagon-head bolt M8.
2. Pull the 2 cable plugs off the oil temperature switch.
3. Remove the shield: unscrew 2 hexagon-head bolts M6x16. Pull out the shield to the clutch side.
Figure shows engine side 1 - 3
4. Remove holder for the main muffler: pull off the electrical plug of ignition coil cyl. 5 and the 2 electrical plugs of the magnetic hydraulic valves. Unscrew 4 hexagon-head bolts: top 2 M8x30, bottom 2 M8x25, then pull out the holder towards the belt pulley side.
5. Remove 3 ignition coils: unscrew 6 hexagon socket head bolts M6x25 and pull the ignition coils out from the spark-plug recess.
6. Remove 2 holders and 2 covers for the magnetic hydraulic valves: unscrew 4 hexagon socket head bolts M6x20, disconnect the connection cable for the hydraulic valves from the sheetmetal bracket and remove the holders. Pull off 2 covers for the hydraulic valves.
See Figures for cylinder bank 1 - 3
7. Remove 2 magnetic hydraulic valves (camshaft and valve lift adjustment). Pull both valves carefully out of the bores. This removal is necessary, because otherwise the exhaust manifold would have to be removed before removing the cylinder head cover.
Pay attention to cleanliness without fail!
8. Remove cylinder head cover. Repeat step 5 as with cylinder bank 1-3.
Installing cylinder head cover - cylinder banks 1 - 3 and 4 - 6
Cylinder bank 4 - 6
Information
- The sealing surfaces of the cylinder heads and the cylinder head covers must be cleaned before the new sealant is applied. Avoid damage!
1. Clean sealing surfaces. Remove any sealant residue from the sealing surfaces on the cylinder head and the cylinder head cover thoroughly with a steel brush. Then rub down with a clean cloth soaked in a degreasing agent (e.g. acetone, solvent naphtha). Make sure that no sealant residue can enter the cylinder head.
2. Replace the 3 seals for the spark-plug recesses.
3. Insert 2 magnetic hydraulic valves and 3 seals for the spark-plug recesses. Fit new O-rings into both the magnetic hydraulic valves and insert into the bores in the cylinder head. (Camshaft adjustment with dowel pin, valve lift control without dowel pin). Replace the 3 seals for the spark-plug recesses.
Only the following sealants may be used to seal the cylinder head cover:
- Three Bond Silicone - type 1209 (beige)
- Loctite 5900 (black)
4. Fit cylinder head cover (as shown in the Figure). Apply a thin bead of sealant on the cylinder head cover. The bead should not be higher than 1.5 mm.
5. Position the 20 hexagon-head bolts M6x30 on the cylinder head cover and 2 hexagon-head bolts M6x20 on the oil extraction pump.
Information
- If the O-ring of the oil extraction pump needs to be replaced, insert the pump after fastening the cylinder head cover and then position the 4 hexagon-head bolts M6x20.
6. Tighten the 20 hexagon-head bolts in the specified tightening sequence with a torque wrench with 13 Nm (9.5 ftlb.).
Tightening torque: 13 Nm (9.5 ftlb.)
7. Tighten the 2 or 4 hexagon-head bolts M6x20 of the oil extraction pump with a torque wrench with 13 Nm (9.5 ftlb.).
Tightening torque: 13 Nm (9.5 ftlb.)
8. Position a new, dry, brown closure cap [diameter] 45 mm on the bore of the exhaust camshaft on the belt pulley side and tap it gently into place with a plastic hammer.
9. Insert 2 green closure caps into the small bores on the clutch side. Position the dry, new closure caps and tap gently into place with a plastic hammer.
10. Fit 2 new covers for the magnetic hydraulic valves.
11. Fit the holders for the magnetic hydraulic valves. Position 4 hexagon socket head bolts M6x20 and tighten with a tightening torque of 10 Nm (7.5 ftlb.).
- A: Holder for camshaft adjustment valve (NVS)
- B: Holder for valve lift adjustment valve (VVS)
12. Fit ignition coils. Insert 3 ignition coils into the spark-plug recesses. Position 2 hexagon socket head bolts M6x25 per ignition coil and tighten with a torque wrench with 10 Nm (7.5 ftlb.).
Tightening torque: 10 Nm (7.5 ftlb.)
13. Fit holder for the main muffler. Position 4 hexagon-head bolts: top 2 M8x30, bottom 2 M8x25, then tighten with a torque wrench with 23 Nm (17 ftlb.). Connect the electrical plug of ignition coil cyl. 5 and the 2 electrical plugs of the magnetic hydraulic valves. Clamp the cables of the hydraulic valves in the sheetmetal brackets.
Tightening torque: 23 Nm (17 ftlb.)
14. Install the shield. Insert the shield, position and tighten the 2 hexagon-head bolts M6x16.
15. Connect the 2 cable plugs on the oil temperature switch.
16. Fit the ground cable on the cylinder head. Tighten the hexagon-head bolt M8 with a torque wrench with 23 Nm (17 ftlb.).
Tightening torque: 23 Nm (17 ftlb.)
Cylinder bank 1 - 3
1. Install the cylinder head cover of cylinder bank 1 - 3 in the same way as for cylinder bank 4 - 6.
